Dependency theory is an economic and social theory that suggests that the resources and wealth of developing countries are exploited by developed countries, leading to a cycle of dependency. It argues that the global economic system is structured in a way that benefits wealthy nations while keeping poorer nations in a state of underdevelopment. This theory emerged in the mid-20th century, influenced by scholars like André Gunder Frank and Immanuel Wallerstein. It emphasizes that historical and structural factors, such as colonialism and unequal trade relationships, contribute to the ongoing economic challenges faced by developing nations.